1. Field of the Invention
The present invention relates to an apparatus and method for fabricating a lenticular plate, more specifically, to an apparatus and method for fabricating a lenticular plate by irradiating with laser light a plate to which a photosensitive material has been deposited.
2. Description of the Related Art
A lenticular plate, also known as a relief lens raster screen, is a plate on which cylindrically symmetric relief lenses of diameters ranging from several hundred xcexcm to several mm are arranged. In general, the lenticular plate is used as a screen for displaying three-dimensional images or multi-view pictures or used as a transmission diffraction grating for diffracting light into a particular direction. An apparatus for displaying three-dimensional images by means of a lenticular plate is described in xe2x80x9cLenticular 3-D Displayxe2x80x9d at pages 341-347 of Compilation of Next Generation Optical Technology, published by Ohutoroniwasu, Co., Japan.
In a conventional method for fabricating a lenticular plate, described in Japanese Laid-Open Patent Publication No. hei-4-35744 for xe2x80x9cA Method for Manufacturing Packaging Material of Diffraction Grating,xe2x80x9d a master plate for the lenticular plate is formed by engraving rows of cylindrically symmetric lens shapes having desired parameters on a metal (e.g., bronze) plate and the lenticular plate is formed by compressing a layer of a plastic, such as acryl or poly chlorovinyl, against the master plate, which functions as a mold. According to this method, however, a new master plate must be formed whenever the characteristics of the lenticular plate is changed. It is also difficult to form lens shapes having different parameters on a single master plate.
According to another conventional method for fabricating a lenticular plate, described in Russian Patent Publication No. SU-1817579 by Ivlyushkm A. N., 1996, a glass plate onto which a. layer of dichromated gelatin (DCG) has been deposited is exposed to an infrared light through a mask having parallel slits. The DCG hardens in proportion to the time-integrated intensity of the light absorbed. The shortcoming of this method is that the DCG layers must be coated and developed two times on the same glass plate. Moreover, a new mask must be formed whenever the characteristics of a lenticular plate are changed.
An object of the present invention is accordingly to provide a low-cost apparatus for fabricating a lenticular plate wherein a new master plate is not required in order to form a lenticular plate having different characteristics.
Another object of the present invention is to provide a method for making a lenticular plate or relief lens raster screen of desired characteristic by applying laser beams to a plate on which a photosensitive material is deposited through a mask which may adjust the intensity of laser beam to solidify the photosensitive material into the form of cylindrical lenses.
In accordance with one aspect of the present invention, an. apparatus for fabricating a lenticular plate by irradiating with laser light a plate to which a photosensitive material is deposited is provided. The apparatus for fabricating a lenticular plate comprises a collimator for collimating a beam from a laser to a predetermined diameter, a mask for adjusting the intensity distribution of the collimated beam, a photoplate on which a layer of photosensitive material is deposited, means for directing the beam which has passed through the mask to a desired region of the photoplate, and means for controlling the mask and the means for directing the beam such that the beam of predetermined intensity distribution irradiates on the desired region of the photoplate.